This disclosure generally relates to wing and tail configurations for aircraft. More specifically, this disclosure relates to swept wings and tails having an engine with an exposed propeller mounted thereon.
When installing an engine with an exposed propeller in front of a wing, the closest approach of the blades to the leading edge of the wing controls how close the engine can be installed to the wing. This distance strongly affects structural fatigue, noise, and interference drag. A rough rule of thumb is that the closest approach should be no closer than 0.35 propeller diameters from the leading edge. For slower sub-sonic aircraft, or engines with only one row of propeller blades, this constraint is less problematic, but for aircraft traveling at high speeds, this causes the engine to be slung further forward on the aircraft, which increases the weight of the engine support structure due to higher static and dynamic loads. Higher local sweep angles in the wake of an exposed propeller engine make the problem worse because, as sweep angle increases, the engine must move further forward to maintain the required clearance. Multiple rows of propeller blades make the problem worse because the engine is longer and the aft-most blades are further aft as a percentage of engine length.
Although the engine can be moved forward to accommodate the required clearance, this would result in longer, heavier, and higher aerodynamic drag engine installations. Alternatively, local wing sweep could be decreased to a less-than-desired amount, which would have the effect of increasing aerodynamic drag.
Accordingly, there is a need for a wing or tail configuration that reduces weight and drag of exposed propeller engine installations and can enable the viable integration of open rotor technology on the wings or tail of commercial aircraft.